A light emitting diode has advantageous features, such as long life, low power consumption, low heat generation, high speed response, high impact resistance, excellent environmental sustainability, and small size, and has been applied to various fields of backlight for liquid crystal display, signal, lighting, display device, and others.
A conventional light emitting diode is produced in a way such that a light emitting diode chip is connected to an interposer, lead frame or substrate by die bonding, and optionally a wiring is formed by wire bonding or the like, followed by resin encapsulation.
Examples of methods for the resin encapsulation include a casting (potting) method in which a light emitting diode chip or the like is embedded in a die and then a liquid resin is charged into the die, followed by curing of the liquid resin, a molding method in which a solid resin is melted by heating and subjected to injection molding using a mold or the like, and a printing method. A casting method is used in the production of so-called shell-type light emitting diode and molding-type light emitting diode, and a molding method is used in, e.g., molding of a plurality of light emitting diode chips at the same time using a lead frame and an organic substrate. With respect to the material for encapsulation, thermosetting epoxy or silicone transparent resins are widely used (Patent document 1).
A single light emitting diode has low intensity of light emission, and therefore a plurality of light emitting diodes are used in combination in some applications. A combination of the light emitting diodes can advantageously be applied to various forms of devices, e.g., a rectangular light emitting device, such as a display, or a rounded light emitting device, such as a signal.
[Patent document 1] Japanese Unexamined Patent Publication No. 2006-165326